The present invention relates to a combination tilting bed carrier and attached wheel-lift apparatus mounted on a chassis of a towing vehicle.
Transporting and towing vehicles such as damaged automobiles and the like, show cars, antique vehicles of various types and other similar types of vehicles has become quite popular in recent years and the development of transport trucks to convey such vehicles has been undertaken.
Transport vehicles having rollback decks are well known as a means for transporting vehicles. One type of transport vehicle having a rollback deck includes a vehicle support surface or the rollback deck movably mounted on a truck bed frame. Specifically, the vehicle support surface is pivotable relative to the truck bed frame between a transport position and a loading position. In the transport position, the support surface is parallel to the bed frame. In the loading position, the support surface is at an angle relative to the bed frame such that it contacts the ground so as allow a disabled vehicle to be rolled thereon.
Another method of towing and transporting vehicles is the wheel-lift apparatus. Typical wheel-lift apparatuses carry disabled vehicles by lifting either the front or rear wheels off the ground, and towing the partially-lifted disabled vehicle on its remaining two wheels. Early versions of the lifting or towing vehicles have a wheel-lift apparatus in which the boom and related lifting mechanism are located beneath the deck of the lifting and towing vehicle. Typically, the wheel-lift apparatus boom has an inner end pivotally mounted adjacent the rear axle and a wheel supporting cradle at an outer end. U.S. Pat. No. 5,061,147, issued to "Nespor" on Oct. 29, 1993, (Reexamination Certificate No. B1 5,061,147, issued on Feb. 25, 1997), entitled "Vehicle Carrier with Wheel-lift", describes a wheel-lift apparatus boom having an inner end pivotally mounted to struts and a bracket adjacent the rear axle and a wheel supporting cradle at an outer end. The boom described in the patent to Nespor is outwardly extended by hydraulic cylinders at an angle raised substantially from horizontal to the ground. Such devices suffer from a number of deficiencies, as explained below.
For example, by utilizing a boom raised at a substantial slope to connect the wheel-supporting cradle to the lifting or towing vehicle, there is a possibility of the supporting cradle or the boom hitting the disabled vehicle, often resulting in significant damage to the disabled vehicle. In some types of vehicles, such as vans and Jeeps, the danger is minimal since there is a very short distance between the bumper and the adjacent wheel axle. However, on vehicles where there is substantial overhang of the body or chassis, beyond the rear and/or front axle the likelihood of damage to the disabled vehicle by the lifting wheel-lift apparatus is significant. A 1996 "CHEVROLET CAMARRO" is an example of a car that is likely to be damaged by many known wheel-lift apparatuses.
U.S. Pat. No. 5,951,235 by C. Young et al. entitled "Advanced Rollback Wheel-Lift" filed Apr. 8, 1997, describes an independent wheel-lift ("IRL") suitable to tow a vehicle behind a car carrier, wrecker or like vehicle. The wrecker includes a bed suitable to support a first vehicle is mounted upon a bed carrier which is pivoted on a first pivot point on the chassis. A first pair of hydraulic cylinders is used to tilt the bed carrier to a ground engaging position to receive a vehicle. An IRL (or wheel-lift or underlift) is mounted to the bed carrier at a second pivot point near the rear wheels of the wrecker, and can thereby be used to tow a second vehicle. The IRL includes a telescopic boom with a second pair of hydraulic cylinders mounted between the boom at the rear end of the wrecker on the bed carrier. The second hydraulic cylinders are positioned to tilt the IRL in an arc about the second pivot point to enable the IRL to approach a ground engaging position. The rear end of the IRL includes a crossbeam, which includes wheel cradles suitable to engage the front wheels of the second vehicle. Once the vehicle wheels are supported by the crossbeam and wheel cradle, the second hydraulic cylinders are retracted to lift one end of the vehicle.
However the device described in U.S. Pat. No. 5,951,235 includes a wheel-lift pivotally mounted on the bed carrier. By mounting the wheel-lift to the bed carrier rather than to the chassis, the amount of weight and stress placed on the bed carrier by the wheel-lift can damage the bed carrier and first pair of hydraulic cylinders over repeated load cycles. If the wheel-lift is mounted to the chassis at the same or a proximate location to the first pivot point of the bed carrier then the weight will be distributed between the chassis and the bed carrier thereby extending the useful life of the bed carrier and the first pair of hydraulic cylinders.
In Horneys et al., U.S. Pat. No. 4,239,275, entitled "Vehicle Transporter," the second pivot point is mounted on the chassis. However, the second hydraulic element between the boom and the bed carrier used a movable bearing rather than a fixed mounting as described in the Nespor patent. A disadvantage of the invention described in the Horneys et al. patent is that as the bed carrier rotated, the second hydraulic elements had to absorb the rotational displacement between the bed carrier rotation about the first pivot point. These rotational induced changes over time can cause wear on the second pivot point and the second hydraulic element, and other related linkage and alignment problems.
In Bubik, U.S. Pat. No. 4,795,303, entitled "Vehicle Transporting Apparatus," the second pivot point is mounted on the chassis. However, the second pivot point is located at a position distant from the first pivot point of the bed carrier. This arrangement places added weight and stress on the first hydraulic element.
The inventions described above also fail to include an effective means for locking the wheel-lift to the bed carrier in the event the second motive means fails. For example in the patent to Nespor, entitled "Vehicle Carrier With Wheel-lift," failure of either of second hydraulic cylinders in the absence of a locking device to secure the boom to the bed carrier in a lifted position could cause a traverse rotation of the boom and accidental displacement of the second vehicle from the wheel cradle. Other inventions use a pin that is placed in one of a series of matching holes on a portion of the bed carrier and the wheel-lift to fix the position of the wheel-lift. However, this arrangement is difficult to use in that it is difficult to align the holes when the wheel-lift is loaded with a vehicle.
None of the patents described above provides the important advantages associated with towing vehicles comprising a boom capable of a substantial reach while maintaining a horizontally aligned or "low angle" approach and lift during loading and carrying. Additionally, a need exists for a tilting bed carrier and wheel-lifting apparatus mounted to the chassis of a car carrying vehicle at a position that will extend the useful life of the bed carrier and a first motive means. Furthermore, the device should be safe and easy to use. The device should also be constructed in a form, preferably in a kit, which will allow users to retrofit old transport vehicles having rollback decks or other similar car carriers.